Allophycocyanin (APC) is a phycobiliprotein with various biological and pharmacological properties. An expression vector containing five essential genes in charge of biosynthesis of cyanobacterial APC holo-alpha subunit (holo-ApcA) was constructed, resulting in over-expression of a fluorescent holo-ApcA in E. coli. After being cultured for 16 h, the dry cell density reached 22.5 g l(-1), and the expression of holo-HT-ApcA was up to 1 g l(-1) broth. The recombinant protein showed similar spectral features to native APC.